SKETCH OF DR. J. W. DRAPER, 367 



pers necessary for the preparation of his work, and to furnish him with 

 statistical information respecting the armies of the United States, their 

 organization, and operations." This order included all the Confederate 

 archives in possession of the War Department. Nor was the interest 

 of the Secretary of War limited to this : he supplied also a large amount 

 of personal information of the utmost value. Access was not unfre- 

 quently given him to documents and correspondence of the most con- 

 fidential kind, with a view of guiding him to correct conclusions, and 

 many of the most decisive military operations are detailed from private 

 memoranda furnished by the commanding officers themselves. As was 

 the case with Dr. Draper's other works, this also has been largely 

 republished in Europe. 



In the summer of 1870 Dr. Draper suffered a severe bereavement in 

 the loss of his wife. Of Brazilian birth, she was connected with an an- 

 cient and noble Portuguese family. She had rendered his domestic 

 life a course of unbroken happiness, and doubtless she was the exem- 

 plar before his eyes when he wrote that often-quoted passage in his 

 " Physiology," in which, after depicting the physical and intellectual 

 peculiarities of woman, he says : " But it is in the family and social rela- 

 tions that her beautiful qualities shine forth. At the close of a long 

 life checkered with pleasures and misfortunes, how often does the aged 

 man with emotion confess that, though all the ephemeral acquaintances 

 and attachments of his career have ended in disappointment and aliena- 

 tion, the wife of his youth is still his friend. In a world from which 

 every thing else seems to be passing away, her affection alone is un- 

 changed, true to him in sickness as in health, in adversity as in pros- 

 perity, true to the hour of death." 



Of their six children, one died in infancy; the survivors are three 

 sons and two daughters. Of the former, the eldest is Professor of 

 Natural History in the College of the City of New York ; the second, 

 Professor of Physiology in the University of New York; the third, 

 Director of the Meteorological Observatory in the New York Central 

 Park. 



After the death of his wife, Dr. Draper spent the following winter 

 in Europe, chiefly in Rome. Since his return he has published two 

 short memoirs : one, on the " Distribution of Heat in the Spectrum," 

 showing that the predominance of heat in the less refrangible regions 

 is due to the action of the prism, and would not be observed in a nor- 

 mal spectrum, such as is formed by a grating ; and that all the rays 

 of light have intrinsically equal heating power. The second is an in- 

 vestigation of the distribution of chemical force in the spectrum. All 

 these scientific researches, to which so many years of his life. have been 

 devoted, have been at his own expense; he has never received any ex- 

 traneous aid, though many of them have been very costly. He has 

 never taken out any patent, but has given the fruits of his investiga- 

 tions and inventions freely to the public. 



